The preparation and self‐assembly of the enantiomers of a series of C3‐symmetric compounds incorporating three tetrathiafulvalene (TTF) residues is reported. The chiral citronellyl and ...dihydrocitronellyl alkyl chains lead to helical one dimensional stacks in solution. Molecular mechanics and dynamics simulations combined with experimental and theoretical circular dichroism support the observed helicity in solution. These stacks self‐assemble to give fibres that have morphologies that depend on the nature of the chiral alkyl group and the medium in which the compounds aggregate. An inversion of macroscopic helical morphology of the citronellyl compound is observed when compared to analogous 2‐methylbutyl chains, which is presumably a result of the stereogenic centre being further away from the core of the molecule. This composition still allows both morphologies to be observed, whereas an achiral compound shows no helicity. The morphology of the fibres also depends on the flexibility at the chain ends of the amphiphilic components, as there is not such an apparently persistent helical morphology for the dihydrocitronellyl derivative as for that prepared from citronellyl chains.
Chiral croissants: Amphiphilic citronellyl‐ and dihydrocitronellyl‐based C3‐ symmetric tris(tetrathiafulvalene) disk‐shaped derivatives have been synthesised. Their self‐assembly properties were investigated by circular dichroism in solution and electronic and optical microscopy in the solid state.
The key concepts of interlocked and intertwined structures and superstructures in chemistry are presented. The relevance of chemical topology when considering interlocked structures is addressed.
A potential new photosensitizer based on a dissymmetric porphyrin derivative bearing a thiol group was synthesized. 5‐4‐(11‐Mercaptoundecyloxy)‐phenyl‐10,15,20‐triphenylporphyrin (PR‐SH) was used to ...functionalize gold nanoparticles in order to obtain a potential drug delivery system. Water‐soluble multifunctional gold nanoparticles GNP‐PR/PEG were prepared using the Brust–Schiffrin methodology, by immobilization of both a thiolated polyethylene glycol (PEG) and the porphyrin thiol compound (PR‐SH). The nanoparticles were fully characterized by transmission electron microscopy and 1H nuclear magnetic resonance spectroscopy, UV/Vis absorption spectroscopy, and X‐ray photoelectron spectroscopy. Furthermore, the ability of GNP‐PR/PEGs to induce singlet oxygen production was analyzed to demonstrate the activity of the photosensitizer. Cytotoxicity experiments showed the nanoparticles are nontoxic. Finally, cellular uptake experiments demonstrated that the functionalized gold nanoparticles are internalized. Therefore, this colloid can be considered to be a novel nanosystem that could potentially be suitable as an intracellular drug delivery system of photosensitizers for photodynamic therapy.
The power of gold! A new thiolated dissymmetrical porphyrin was synthesized and consequently immobilized onto gold nanoparticles using the Brust–Schiffrin method. Thiolated polyethylene glycol was added to obtain water‐soluble nanoparticles. The nanoparticles could be internalized by cells and were nontoxic. Tests on the ability of the functionalized gold nanoparticles to induce singlet oxygen production point to a promising nanosystem for photodynamic therapy.
Coordination-driven gelation of a benzothiadiazole-fused tetrathiafulvalene (TTF) is demonstrated. This is the first work reporting highly stable metallogels based on a donor-acceptor conjugate with ...such a simple structure for the construction of new low-bandgap materials with various functional properties and novel nanostructures.
Changing abruptly the potential between a scanning tunneling microscope tip and a graphite substrate induces “high-conductance” spots at the molecular level in a monolayer formed by a manganese ...chloride–porphyrin molecule. These events are attributed to the pulse-induced formation of μ-oxo-porphyrin dimers. The pulse voltage must pass a certain threshold for dimer formation, and pulse polarity determines the yield.
Display omitted
Protein orientation in nanoparticle-protein conjugates plays a crucial role in binding to cell receptors and ultimately, defines their targeting efficiency. Therefore, understanding ...fundamental aspects of the role of protein orientation upon adsorption on the surface of nanoparticles (NPs) is vital for the development of clinically important protein-based nanomedicines. In this work, new insights on the effect of the different orientation of cytochrome c (cyt c) bound to gold nanoparticles (GNPs) using various ligands on its apoptotic activity is reported. Time-of-Flight Secondary-Ion Mass Spectrometry (ToF-SIMS), electrochemical and circular dichroism (CD) analyses are used to investigate the characteristics of cyt c orientation and structure on functionalized GNPs. These studies indicate that the orientation and position of the heme ring inside the cyt c structure can be altered by changing the surface chemistry on the GNPs. A difference in the apoptosis inducing capability because of different orientation of cyt c bound to the GNPs is observed. These findings indicate that the biological activity of a protein can be modulated on the surface of NPs by varying its adsorption orientation. This study will impact on the rational design of new nanoscale biosensors, bioelectronics, and nanoparticle-protein based drugs.
Recent synthesis of covalent organic assemblies at surfaces has opened the promise of producing robust nanostructures for functional interfaces. To uncover how this new chemistry works at surfaces ...and understand the underlying mechanisms that control bond-breaking and bond-making processes at specific positions of the participating molecules, we study here the coupling reaction of tetra(mesityl)porphyrin molecules, which creates covalently connected networks on the Cu(110) surface by utilizing the 4-methyl groups as unique connection points. Using scanning tunneling microscopy (STM), state-of-the-art density functional theory (DFT), and Nudged Elastic Band (NEB) calculations, we show that the unique directionality of the covalent bonding is found to stem from a chain of highly selective C–H activation and dehydrogenation processes, followed by specific intermolecular C–C coupling reactions that are facilitated by the surface, by steric constraints, and by anisotropic molecular diffusion. These insights provide the first steps toward developing synthetic rules for complex two-dimensional covalent organic chemistry that can be enacted directly at a surface to deliver specific macromolecular structures designed for specific functions.
We describe the synthesis and characterisation of the first of a new class of soluble ladder oligomeric thermoelectric material based on previously unutilised ethene-1,1,2,2-tetrasulfonic acid. ...Reaction of Ba(OH)
2
and propionic acid at a 1:1 stoichiometry leads to the formation of the previously unrecognised soluble Ba(OH)(O
2
CEt)⋅H
2
O. The latter when used to hydrolyse 1,3,4,6-tetrathiapentalene-2,5-dione (TPD), in the presence of NiCl
2
, forms a new material whose elemental composition is in accord with the formula (EtCO
2
Ba)
4
Ni
8
{(O
3
S)
2
C = C(SO
3
)
2
}
5
⋅22H
2
O (
4
). Compound
4
can be pressed into pellets, drop-cast as DMSO solutions or ink-jet printed (down to sub-mm resolutions). While its room temperature thermoelectric properties are modest (σ
max
0.04 S cm
−1
and Seebeck coefficient, α
max
− 25.8 μV K
−1
) we introduce a versatile new oligomeric material that opens new possible synthetic routes for n-type thermoelectrics.
Graphical Abstract
PDF
